Show Complex imag components directly (#53529)
Fixes #52100.
This avoids doing math on the imaginary component — and instead just
asks if their string representation starts with a `-` to determine
whether the operator between the components should be `+` or `-`.
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Co-authored-by: Jameson Nash <vtjnash@gmail.com>
Co-authored-by: Dilum Aluthge <dilum@aluthge.com>
